Features of a CPT-based atomic clock with pumping by different-order sidebands of a VCSEL's frequency

Abstract

Presented for the first time is our research into reduction of energy consumption of miniaturised Rb atomic clocks based on coherent population trapping (CPT) effect at lowered microwave modulation frequency. We studied properties of a CPT-based atomic frequency standard pumped with multi-frequency radiation from sidebands of a single-frequency semiconductor laser whose injection current was modulated at subharmonics (1/2–1/6) of the frequency of Rb hyperfine ground state splitting. Pumping by third-order sidebands is the optimum when the atomic clock stability drops only slightly (by 11%), whereas energy consumption of the microwave components is reduced by a factor of 1.5.